The population of gray seals around Nantucket Sound is rising 20 percent a year (according to Betty Lentell of the Woods Hole Oceanographic Institute) to an estimated 15,000, but that’s the wrong direction as far as some fishermen are concerned.

“They should take the population to where it was 20 years ago and maintain it,” surfcaster Craig Poosikian suggested during a break in Saturday’s Cape Seal Symposium at Chatham High School, organized by Cape Cod Commercial Hook Fishermen’s Association. “Make it a commercial venture.”

Seals are protected by the Marine Mammal Protection Act of 1972 and the last bounty for a Massachusetts seal nose was paid in 1960.

“There’s no fish to catch – is that an impact?” Poosikian asked. “Every spring the for the last 10 years you get your typical inshore fishery; striped bass, bluefish, scup, they show up and then they scram by June 1. I used to go the Nauset Beach throw a line in the sea and get a two-pound flounder, striped bass, dogfish. I can’t even get a skate off Nauset Beach anymore. I call it the gray curtain. I used to make a living on the beach.”

The gray curtain is the seal patrol as they fan along the outer Cape.

“Now they’re everywhere, in Sandwich, Cape Cod Bay. It’s not a Chatham thing anymore,” Capt. Tom Smith noted. “I grew up casting for bass and bluefish off Nauset Beach, all us kids, you can’t do that now because of the seals. They ruined the surf fishing.”

Rebecca Gast of WHOI noted the three biggest haul-out spots are High Head in Truro, Jeremy Point in Wellfleet and North Island in Chatham.

“Just the day before yesterday I came around Monomoy Point and counted no less than 4,000 seals hauled out on the beach,” fisherman Bill Amaru said. “They were 15 to 20 deep in one section more than a quarter mile long.”

And seals eat fish, sometimes right out of the fishermen’s nets. They bite the belly out, leaving the bones, so that dinner won’t show up in an analysis of stomach contents. That’s one reason some fishermen want more action and less reflection.

“It boggles my mind that we need more studies and more data,” Robert Fitzpatrick said. “If you let this go four or five more years, it’s over and ground-fish will never recover.”

“Our way of life and our future is on the line,” Amaru said. “The amount of fish we can catch was reduced 70 percent this year. The population of seals is studied ad nauseum.”

“We’ve heard a lot of talk about studies and information but no talk about what the next step is going to be,” Nick Muto agreed. “We already know we have a problem with seals. They’re impacting our lives and businesses.”

But Greg Early of the New England Aquarium is skeptical that culling the seal population will bring back fading fish populations.

“Canada has a culling program on the books. There’s never been demonstrated evidence it has improved the fishery,” Early remarked. “I can’t find such a paper. What if it doesn’t work that way? I’m a skeptic. Before I go pulling the plug on a population I want to know more about it.”

Early argued that the seals might be eating fish they prey on cod, or prey on the fish cod like to eat.

The fishermen have other concerns as well.

“I’m more concerned with the health of fish because the presence of worms that weaken the fish. The last four or five years have seen a failure of recruitment of fish,” Amaru said.

The seals could be a reservoir for the worms

“They can be part of the system of parasites, as a host for parasites (such as cod worm) later found in fish,” Lentell noted.

Ernie Eldredge is a weir fisherman and seals find his weirs a pleasant interlude. Owen Nichols of Provincetown Center For Coastal Studies attached a camera to the weir to watch the seals.

“On one recording we saw 290 instances of a seal passing the sensor,” Nichols recalled. “We found it’s not associated with fishing effort, often it’s a night when we’re not around. There’s no ‘dinner bell’. Not only are they consuming fish in the weirs, it’s likely they’re driving them out as well. Sometimes all you find in the bowl are pieces of fish and there are no swimming things.”

Using pingers to drive seals away hasn’t worked, as the seals quickly become habituated to them.

Of course, great white sharks have arrived after the seals, to provide some natural control.

“The smaller white sharks, less than three meters, feed on fish,” state shark expert Greg Skomal explained. “Once they get over three meters they shift to seals and cetaceans (mostly dead whales). The sharply pointed teeth and smaller jaw leads to feeding on fish. When they grow in length the jaw becomes bigger and the teeth more serrated, as a cutting tool and they become a marine mammal predator and scavengers.”

Hopefully they won’t scavenge any more swimmers off Truro.

“If you open a café the predators will come,” Skomal said. “Those sharks are here to stay so long as the seal population is robust.”

There is a seal tourism industry. Keith Lincoln, who operates a ferry to Monomoy, said he’s up to four boats four times a day.